Method and Apparatus for Allocating and Processing Sequences in Communication System

ABSTRACT

A method and apparatus for allocating and processing sequences in a communication system is disclosed. The method includes: dividing sequences in a sequence group into multiple sub-groups, each sub-group corresponding to its own mode of occupying time frequency resources; selecting sequences from a candidate sequence collection corresponding to each sub-group to form the sequences in the sub-group by: the sequences in a sub-group i in a sequence group k being composed of n sequences in the candidate sequence collection, the n sequences making a |r i /N i −c k /N p     1   | or |(r i /N i −c k /N p     1   ) modu m k,i | function value the smallest, second smallest, till the n th  smallest respectively; allocating the sequence group to cells, users or channels. It prevents the sequences highly correlated with the sequences of a specific length from appearing in other sequence groups, thus reducing interference, avoiding the trouble of storing the lists of massive sequence groups.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.14/068,124, filed on Oct. 31, 2013, which is a continuation of U.S.patent application Ser. No. 13/545,707, filed on Jul. 10, 2012, now U.S.Pat. No. 8,588,168, which is a continuation of U.S. patent applicationSer. No. 12/493,869, filed on Jun. 29, 2009, now U.S. Pat. No.8,249,006, which is a continuation of International Application No.PCT/CN2008/070431, filed on Mar. 6, 2008. The International Applicationclaims priority to Chinese Patent Application No. 200710073057.4, filedon Mar. 7, 2007, Chinese Patent Application No. 200710100449.5, filed onApr. 9, 2007, Chinese Patent Application No. 200710103147.3, filed onApr. 27, 2007, Chinese Patent Application No. 200710112774.3, filed onJun. 17, 2007, Chinese Patent Application No. 200710123676.X, filed onSep. 30, 2007, all of which are hereby incorporated by reference intheir entireties.

FIELD OF THE APPLICATION

The present application relates to the communication field, and inparticular, to a technology for allocating and processing sequences in acommunication system.

BACKGROUND OF THE APPLICATION

In the communication system, the Constant Amplitude ZeroAuto-Correlation (CAZAC) sequence is a very important communicationresource. The specific features are as follows:

The modulo of the amplitude is a constant value, for example, normalizedto 1; and

Zero periodical-auto-correlation: except the maximum correlation withthe sequence itself the auto correlation with other cyclic shift of thissequence is zero.

The CAZAC sequence has the above features. Therefore, after Fouriertransformation, the sequence in the frequency domain is also a CAZACsequence. The sequence of this feature may be used as a reference signalfor channel estimation in the communication.

For example, in a Single Carrier Frequency Division Multiple Access(SC-FDMA) system, within a symbol time, the elements of the CAZACsequence are transmitted sequentially on multiple sub-carriers. If thereceiver knows the sequence of the transmitted signals, the receiver mayperform channel estimation by using the received signals. Thetransmitted signals have equal amplitudes on every sub-carrier on thefrequency domain. Therefore, the receiver may estimate out the channelfading on each sub-carrier fairly. In addition, due to the constantamplitude feature of the CAZAC sequence on the time domain, thepeak-to-average value of the transmitted waveform is relatively low,which facilitates transmitting.

In another example, the random access preamble signals in the SC-FDMAsystem may be made of CAZAC sequences. The preamble sequence of therandom access signals may be modulated on the frequency domainsub-carrier, and transformed onto the time domain through Fouriertransformation before being transmitted. In this way, through high autocorrelation and cross correlation of the CAZAC sequence, littleinterference exists between the random access preamble signals ofdifferent cells and different users.

A CAZAC signal is manifested as a CAZAC signal on both the time domainand the frequency domain. Therefore, the CAZAC signals may also bemodulated directly into signals on the time domain that occupies certainbandwidth before being transmitted.

The CAZAC sequence comes in many types. A common type is Zadoff-Chusequence. Other types include: Generalized Chirplike Sequence (GCL) andMilewski sequence. Taking the Zadoff-Chu sequence as an example, thegeneration mode or expression of a Zadoff-Chu sequence is as follows:

$\begin{matrix}{{a_{r,N}(k)} = \left\{ \begin{matrix}{\exp \left\lbrack {{- \frac{j\; 2\; {\pi \cdot r}}{N}}\left( {{q \cdot k} + \frac{k \cdot \left( {k + 1} \right)}{2}} \right)} \right\rbrack} & \begin{matrix}{{N\mspace{14mu} {is}\mspace{14mu} {an}\mspace{14mu} {odd}\mspace{14mu} {number}},} \\{{k = 0},1,\ldots \mspace{14mu},{N - 1}}\end{matrix} \\{\exp \left\lbrack {{- \frac{j\; 2\; {\pi \cdot r}}{N}}\left( {{q \cdot k} + \frac{k^{2}}{2}} \right)} \right\rbrack} & \begin{matrix}{{N\mspace{14mu} {is}\mspace{14mu} {an}\mspace{14mu} {even}\mspace{14mu} {number}},} \\{{k = 0},1,\ldots \mspace{14mu},{N - 1}}\end{matrix}\end{matrix} \right.} & {{Formula}\mspace{14mu} (1)}\end{matrix}$

wherein r is a parameter generated by the sequence and is relativelyprime to N, and q is an integer. When the value of r varies, thesequence differs. r is named as a basic sequence index, and qcorresponds to different cyclic shifts. That is, the r value determinesthe basic sequence, and the q value determines different cyclic shiftsof the same basic sequence. The sequence generated by different cyclicshifts of a sequence is known as a cyclic shift sequence generated bythe same basic sequence. For two different r values such as r=u,r=v,when (u−v) is relatively prime to N, the two sequences are highlycross-correlated. When N is a prime number, r=1, 2, . . . , N−1, and N−1different CAZAC sequences are generated. Such sequences are highlycross-correlated. In the above example, when N is a prime number, theabsolute value of cross correlation normalized between the two sequencesis √{square root over (N)}. The conjugate of the Zadoff-Chu sequence isalso a CAZAC sequence.

In a general cellular communication system, when a cell selects asequence for modulation and transmission, another cell needs to selectanother sequence having the feature of low cross correlation. Forexample, in the case of using a Zadoff-Chu sequence, if N is a primenumber, each cell selects a different r value, thus ensuring low crosscorrelation and low interference.

The modulated signals transmitted by a cell may also adopt the fragmentsof the old sequence or repeat cyclically, which also maintains the autocorrelation and cross correlation features of the old sequence properly.Particularly, when the number of sub-carriers that bear the sequence inthe cell is not a prime number, it is necessary to select the sequencewhose length is equal to the prime number around the number ofsub-carriers, and the desired sequences are obtained throughsegmentation or cyclic extension of the sequences before beingtransmitted. In the following description, the operations ofsegmentation or cyclic extension of the sequence are omitted.

When the signals of multiple sequences transmitted by different cellsoccupy the same time frequency resource, the sequences transmitted bycell A and cell B have the same length, as shown in FIG. 1. For example,two different Zadoff-Chu sequences whose length is a prime number N maybe selected. When the basic sequence index of one sequence is differentfrom that of the other, the two sequences are little correlated, and thetransmitted signals of different cells are little mutual-interfering.

As shown in FIG. 2, when the signals of the modulated sequence occupydifferent time frequency resources, some users of cell A transmitsequence-modulated signals on the radio resource with bandwidth B1;meanwhile, some users of cell B transmit sequence-modulated signals onthe radio resource with bandwidth B2, and the time frequency resourcesof the two parts overlap. In the system shown in FIG. 2, all cells havethe same sub-carrier width. Within bandwidth B1, 36 sub-carriers exist.Within bandwidth B2, 144 sub-carriers exist. Because the sequence ismapped onto a sub-carrier, the length of the sub-carrier corresponds tothe length of the sequence. Evidently, the two cells need to selectsequences of different lengths respectively. In this case, the crossinterference may be strong between the long sequence and the shortsequence, and the sequence planning becomes relatively complex. In theexample shown in FIG. 2, only sequences of two lengths exist. Inpractice, depending on the size of different radio resources occupied bya user's transmission, more sequences of different lengths may exist,and the complexity is higher.

The foregoing modulated signals of the sequences that occupy differenttime frequency resources occur frequently in the SC-FDMA system. Becausethe sequence serves as a reference signal and provides the channelestimation required by data demodulation, the sequence is transmittedalong with the bandwidth resources of the data. The data bandwidth ofthe user may have different bandwidth values and locations at differenttimes according to specific scheduling rules. Therefore, the sequence ofthe reference signal of each different cell occupies the time frequencyresources in a way that is frequently changing, and the interferencebetween cells is affected by the correlation of sequences of differentlengths. To make matters worse, the system generally uses the shiftcorrelation feature of sequences, obtains multiple code divisionquadrature sequences through different cyclic time shifts, and allocatesthem to different users. Therefore, once strong interference occursbetween the sequences of two lengths, the users who use the sequences ofthe two lengths may interfere with each other strongly.

Nevertheless, the modes of the sequence occupying the time frequencyresources are not limited to the foregoing examples. For example,sequences of different lengths may be modulated on the time domain atthe same sampling frequency, which also brings the issue of correlationbetween the long sequence and the short sequence.

Alternatively, the sequence may occupy the frequency domain sub-carriersat different sub-carrier intervals, or occupy the time sampling pointsat different time sampling intervals. In other words, the sequence isnot modulated on all sub-carriers/sampling points, but modulated atregular intervals equivalent to a specific number ofsub-carriers/sampling points.

To sum up, when the sequence occupies the time frequency resource indifferent modes, the interference among cells is relatively complex.Particularly, when sequences of different lengths exist, the sequencesof each length need to be planned separately, and the interference amongsequences with different length needs to be considered in a system withmultiple cells.

SUMMARY OF THE APPLICATION

An embodiment of the present application provides a method forallocating sequences in a communication system. The method includes:

dividing sequences in a sequence group into multiple sub-groups, whereeach sub-group corresponds to its own mode of occupying time frequencyresources;

selecting sequences from a candidate sequence collection correspondingto each sub-group to form sequences in the sub-group in this way: thesequences in a sub-group i (i is a serial number of the sub-group) in asequence group k (k is a serial number of the sequence group) arecomposed of n (n is a natural number) sequences in the candidatesequence collection, where the n sequences make the|r_(i)/N_(i)−c_(k)/N_(p) ₁ | or |(r_(i)/N_(i)−c_(k)/N_(p) ₁ ) modum_(k,i)| function value the smallest, second smallest, till the n^(th)smallest respectively; N_(p) ₁ is the length of a reference sub-groupsequence, c_(k) is a basic sequence index of a sequence with a length ofN_(p) _(i) determined by the sequence group k; r_(i) is a basic sequenceindex in the candidate sequence collection, and N_(i) is the length of asequence in the candidate sequence collection; m_(k,i) is a variabledependent on the group number k and the sub-group number i; and

allocating the sequence groups to the cells, users or channels.

A method for processing sequences provided in an embodiment of thepresent application includes:

-   -   obtaining a group number k of a sequence group allocated by the        system;

selecting n (n is a natural number) sequences from a candidate sequencecollection to form sequences in a sub-group i (i is a serial number ofthe sub-group) in a sequence group k, where the n sequences make the|r_(i)/N_(i)−c_(k)/N_(p) ₁ | or |(r_(i)/N_(i)−c_(k)/N_(p) ₁ ) modum_(k,i)| function value the smallest, second smallest, till the n^(th)smallest respectively, NA is the length of a reference sub-groupsequence, c_(k) is a basic sequence index of a sequence with a length ofN_(p) ₁ determined by the sequence group k; r_(i) is a basic sequenceindex in the candidate sequence collection, and N_(i) is the length of asequence in the candidate sequence collection; m_(k,i) is a variabledependent on the group number k and the sub-group number i; and

generating a corresponding sequence according to the sequences in theformed sub-group, and transmitting or receiving the sequences on thetime frequency resources corresponding to the sub-group i.

An apparatus for processing sequences provided in an embodiment of thepresent application includes:

a sequence selecting unit, adapted to: obtain a group number k of asequence group allocated by the system, and select n (n is a naturalnumber) sequences from a candidate sequence collection to form sequencesin a sub-group i (i is a serial number of the sub-group) in the sequencegroup k (k is a serial number of the sequence group), where the nsequences make the |r_(i)/N_(i)−c_(k)/N_(p) ₁ | or|(r_(i)/N_(i)−c_(k)/N_(p) ₁ ) modu m_(k,i)| function value the smallest,second smallest, and the n^(th) smallest respectively, N_(p) ₁ is thelength of a reference sub-group sequence, c_(k) is a basic sequenceindex of a sequence with a length of N_(p) ₁ determined by the sequencegroup k; r_(i) is a basic sequence index in the candidate sequencecollection, and N_(i) is the length of a sequence in the candidatesequence collection; m_(k,i) is a variable dependent on the group numberk and the sub-group number i; and

a sequence processing unit, adapted to: generate a correspondingsequence according to the sequences in the formed sub-group i, andprocess the sequences on the time frequency resources corresponding tothe sub-group I, where the processing includes transmitting andreceiving.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the conventional art where the sequences transmitted bydifferent cells occupy the same time frequency resources and have thesame length;

FIG. 2 shows the conventional art where the sequences transmitted bydifferent cells occupy partially overlapped time frequency resources andhave different lengths;

FIG. 3 shows a calculation process for determining u and v in anembodiment of the present application;

FIG. 4 is a flowchart of a sequence processing method in an embodimentof the present application;

FIG. 5 shows a structure of a sequence processing apparatus in anembodiment of the present application;

FIG. 6 shows a structure of a sequence processing apparatus in anembodiment of the present application; and

FIG. 7 shows a structure of a sequence processing apparatus in anotherembodiment of the present application.

DETAILED DESCRIPTION OF THE APPLICATION

A detailed description of the present application is provided hereunderwith reference to accompanying drawings and preferred embodiments.

In the Chinese application No. 200610173364.5, which was filed with theState Intellectual Property Office of the People's Republic of China byHuawei Technologies Co., Ltd. on Dec. 30, 2006, a method is provided toovercome the sequence interference caused by different modes ofoccupying time frequency resources by grouping sequences. The methodshows: the sequences in a group are multiple sequences corresponding todifferent modes of occupying time frequency resources; the stronglycorrelated sequences are included into a group, and the correlationbetween different groups is relatively low; and then the sequence groupsare allocated among the cells. The strongly correlated sequences are inthe same group, and the sequences in the same group are used only inthis group. The sequence groups used by different cells are littlecorrelated with each other, thus avoiding strong correlation in the caseof using sequences of different lengths in different cells.

The strongly correlated sequences are included into a group. Generally,the composition of all sequences of each group may be stored. When acell user or channel wants to use a sequence corresponding to a mode ofoccupying time frequency resources in the allocated sequence group, thedesired sequence may be found in the stored sequence group. However, theformation of the sequence group needs a pre-stored table. If the size ofthe sequence group becomes greater, the storage occupies a huge space,and the searching is time-consuming. The extra storage increases thecomplexity and wastes hardware resources.

Embodiment 1

In this embodiment, the system allocates sequence groups to the cell,user or channel. The sequences in each sequence group are divided intomultiple sequence sub-groups. Each sequence sub-group corresponds to amode of occupying time frequency resources. In the communication system,each mode of occupying time frequency resources corresponds to asequence sub-group uniquely. The sequences in each sub-group areselected from the candidate sequence collection corresponding to thesub-group in a specific selection mode. According to the allocatedsequence group and the mode of occupying time frequency resources usedfor the specific transmit signals, the user or channel selects thesequences in the sequence sub-group corresponding to the mode ofoccupying the time frequency resources of the transmit signals in theallocated sequence group for transmitting or receiving.

A certain selection mode can be: for a random sub-group i, determining afunction ƒ_(i) ^((·)) corresponding to the sub-group, where the domainof the function is the candidate sequence collection corresponding tothe sub-group; determining n sequences from the candidate sequencecollection to form sequences, n is a natural number, in the sub-group i,i is a serial number of the sub-group, in the sequence group k, k is theserial number of the sequence group, where the n sequences make theƒ_(i) ^((·)) function value the smallest, second smallest, and thirdsmallest respectively, d(a,b) is a two variables function, and G_(k) isa variable determined by the group number k. This selection mode isequivalent to: selecting n sequences from the candidate sequencecollection to make the d(ƒ_(i)(·), G_(k)) of all other sequences greaterthan d(ƒ_(i)(·), G_(k))) of these n sequences.

The foregoing sequence selection mode is described below, taking aZadoff-Chu sequence, namely, a_(r,N)(z), in the CAZAC sequence as anexample:

Each sequence group is composed of M sub-groups. The candidate sequencecollection of sub-groups 1, 2, . . . , M includes the Zadoff-Chusequences whose lengths are N₁, N₂, . . . , N_(M). The Zadoff-Chusequence whose length is N_(i), namely, the a_(r) _(i) _(, N) _(i) (z),z=0, 1, . . . , N_(i)−1 sequence, has N_(i)−1 different basic sequences,depending on r_(i)=1, 2, . . . , N_(i)−1. Specifically, the functioncorresponding to the sub-group i (namely, the sub-group i correspondingto the Zadoff-Chu sequence whose length is N_(i)) is ƒ_(i):{a_(r) _(i)_(N) _(i) (z)}_(z=0, 1, 2, . . . , N) _(i) ⁻¹→r_(i)/N_(i). The domain ofthis function is a candidate sequence collection corresponding to thesub-group i. r_(i) is an index of the Zadoff-Chu sequence in thecandidate sequence collection, and N_(i) is the length of the Zadoff-Chusequence in the candidate sequence collection.

For the sequence group k=1, 2, . . . , the sub-group numbered p₁ isselected as a reference sub-group. The foregoing G_(k) is defined as

G_(k) = f_(p₁)({a_(c_(k), N_(p₁))(z)}_(z = 0, 1, …, N₁ − 1)) = c_(k)/N_(p₁),

N_(p) ₁ is the length of the reference sub-group sequence, and Ck is abasic sequence index of the sequence with a length of N_(p) ₁ determinedby the sequence group k. Particularly, if c_(k)=k is selected, then

G_(k) = f_(p₁)({a_(k, N_(p₁))}) = k/N_(p₁).

If the foregoing function d(a, b) is defined as |a−b|, the sequence thatmakes the d(ƒ_(p) ₁ (·),G_(k)))=d(ƒ_(p) ₁ (·), ƒ_(p) ₁ ({a_(k,N) _(p1)})) value the smallest in the sub-group numbered p₁ in the sequencegroup k is the {a_(k,N) _(p1) } sequence with the index of r_(p) ₁ =kand length of N_(p) ₁ . In this case, d(ƒ_(p) ₁ (·),G_(k)=0.

The sequences in the sub-group i=m in the sequence group k are nsequences that have the length of N_(m) and make the|r_(m)/N_(m)−k/N_(p) ₁ | value the smallest, second smallest, and thirdsmallest respectively, namely, n sequences that make thed(ƒ_(m)(·),ƒ_(p) ₁ ({a_(k,N) _(p1) }) value smaller, where n is anatural number dependent on k and m.

The foregoing embodiment reveals that: the sequences (for example, i=m,j=p₁) in at least two sub-groups i and j in at least one sequence groupk are n (n is a natural number dependent on k, i, and j) sequencesselected from the candidate sequence collection and make the value ofthe function d(ƒ_(i)(·),ƒ_(j)(·)) such as the foregoing d(ƒ_(m)(·),ƒ_(p) ₁ ({a_(k,N) _(p1) }) smallest, second smallest, and third smallestrespectively.

This embodiment is introduced below, taking a non-CAZAC sequence such asa Gauss sequence which has high auto correlation and cross correlationfeatures as an example. A formula for generating a Gauss sequence is:

b _(α) ₁ _(,α) _(i−1) _(, . . . , α) ₀ (n)=exp(−2πj(α₁ n ^(l)+α_(l−1) n^(l−1)+ . . . +α₀)), n=0, 1, 2, . . . , N  Formula (2)

In formula (2), n^(l) is the highest-order item of the Gauss sequence, lis the highest order, and the value range of l is a positive integer. Ifl=2, α₂=r/N, where N is a positive integer. If N=2N₁ and α₁=r(N₁ mod2)/N+2r/N·p, the Gauss sequence is equivalent to a Zadoff-Chu sequenceα_(r,N) ₁ (n) whose indexes are r, N₁. if l>2, different α_(l)=r/(Nl),r=1, 2, . . . , N−1 values correspond to different Gauss sequencegroups, and each group has multiple sequences which depend on thelower-order coefficients α_(l−1), α_(l−2), . . . . In this case, theGauss sequence is not a CAZAC sequence, but has high auto correlationand cross correlation features. In this embodiment, α_(r,N)(n) is usedto represent multiple sequences b_(α) ₁ _(,α) _(l−1) _(, . . . α) ₀ (n)of α_(l)=r/(lN). One of such sequences is defined as a basic sequence.

For a Gauss sequence α_(r,N)(z), the function corresponding to thesub-group i may be defined as ƒ_(i): {a_(r) _(i) _(N) _(i)(z)}_(z=0, 1, 2, . . . ,N) _(i) ⁻¹→r_(i)/N_(i). The domain of thisfunction is a candidate sequence collection corresponding to thesub-group i. In the function, r_(i) is an index of the Gauss sequence inthe candidate sequence collection, and N_(i) is the length of the Gausssequence in the candidate sequence collection.

The function d(a,b) corresponding to the Gauss sequence may bed(a,b)=|(a−b) modu 1|, where the modu 1 operation is defined as makingthe modulo value included in (−½,½].

Particularly, for the Zadoff-Chu sequence which can be construed as aspecial example of the Gauss sequence, if the basic sequence index isr=−(N−1)/2, . . . , −1, 0, 1, . . . , (N−1)/2, because |a−b<½, the modu1 operation is not required.

However, for general Gauss sequences such as r=1, 3, 5, . . . ,N₁−2,N₁+2, . . . , 2N₁−1, N=2N₁, l=2, α₂=r/(2N₁),α₁=0, andα_(r,N)(z)_(z=−(N) ₁ _(−1)/2, . . . . , −1, 0, 1, 2, . . . . , (N) ₁_(−1)/2), (d(a,b)=(a−b)modu 1| is required. In other words, d(ƒ_(i),ƒ_(j)) of the sequences corresponding to α₂=r_(i)/(2N_(i)) and thesequences corresponding to α₂=r_(j)/(2N_(j)) is

${{d\left( {f_{i},f_{j}} \right)} = {{{{r_{i}/N_{i}} - {{r_{j}/N_{j}}\; {modu}\mspace{14mu} 1}}} = {\frac{\left( {{r_{i}N_{j}} - {r_{j}N_{i}}} \right){modu}\mspace{14mu} N_{i}N_{j}}{N_{i}N_{j}}}}},$

where the modu N_(i)N_(j) operation is defined as making the modulovalue included in (−N_(i)N_(j)/2, N_(i)N_(j)/2]. If l=3 and d(ƒ_(i),ƒ_(j)) of the sequences corresponding to α₃=r_(i)/(3N_(i)) and thesequences corresponding to α₃=r_(j)/(3N_(j)) isd(ƒ_(i),ƒ_(j))=|(r_(i)/N_(i)−r_(j)/N_(j))modu 1| and l=4, 5, . . . , theprocessing is similar.

The Gauss sequence may be defined in another way. If α_(l)=r_(i)/N, andα_(r) _(i) _(,N) is used to represent the corresponding Gauss sequence,then the foregoing ƒ_(i) of the function is defined as ƒ_(i):a_(r) _(i)_(,N) _(i) (z)→r_(i)/N_(i), and the function d(a,b) is defined asd(a,b)=|(a−b) modu 1/l|, where the modu 1/l operation makes −1(2l)<(a−b)modu 1/l≦1/(2l). Therefore, the definition of the two types of Gausssequences generates the same sequence group. The definition of such ameasurement function is also applicable to the Zadoff-Chu sequence.

In another embodiment, if the mode of occupying time frequency resourcesis that the sequence is modulated on the radio resource whosesub-carrier interval (or time domain sampling interval) is s, then thefunction corresponding to the sub-group with the interval s is: ƒ_(N)_(i) .:{a_(s) ₂ _(r) _(i) _(,N) _(i) (z)}_(z=0, 1, 2, . . . , N) _(i)⁻¹→r_(i)/N_(i), where s is the sub-carrier (or time domain sampling)interval of the radio resource. For a Gauss sequence, the function isƒ_(N) _(i) :{a_(s) _(i) _(r) _(i) _(,N) _(i) (z)}_(z=0, 1, 2, . . . , N)_(i) ⁻¹→r_(i)/N_(i), where l is the highest order of the Gauss sequence.

The foregoing reference sub-group is set according to multiple factors.A sub-group of a specific sequence length may be selected as a referencesub-group.

Preferably, the sub-group with the minimum sequence length in the systemis selected as a reference sub-group. The quantity of available sequencegroups in the system is the same as the quantity of sequences of thislength. Therefore, shorter sequences do not appear repeatedly indifferent sequence groups. For example, supposing the shortest sequencelength according to the resource occupation mode is 11 in the system,then in the foregoing method, N_(p) ₁ =N₁=11. In this case, 10 sequencegroups are available in the system.

Alternatively, the sub-group with the maximum sequence length in thesequence group may be selected as a reference sub-group. For example,the maximum sequence length in the sequence group is 37, and a sub-groupwith the sequence length 37 is selected as a reference sub-group. Inthis case, N_(p) ₁ =N₂=37, and 36 sequence groups are available. When r₂meets −1/(2N_(i))<r₂/N₂<1/(2N₁), if the value of r₁ is not limited tor₁=1, 2, . . . , N₁−1, then r₁ that makes the |r₂/N₂−r₁/N₁| value thesmallest is 0. In practice, the value 0 of r₁ does not correspond to theZadoff-Chu sequence. Therefore, r₂ that makes −1/(2N₁)<r₂/N₂<1/(2N₁),namely, r₂=+1,−1, may be removed. In this way, there are 34 groups ofsequences in total. In a sequence group, the quantity of the shortestsequences is less than 36. Therefore, the shortest sequences are usedrepeatedly.

Moreover, the reference sub-group may be a default sub-group of thesystem, and may be set by the system as required and notified to theuser. After a sequence in the reference sub-group j is selected, thesequences in the sub-group i are n sequences that make the d(ƒ_(i)(·),ƒ_(j)(·)) value smaller, and are in the sequence group that contain thesequences selected for the reference sub-group j. Different sequencegroups are generated by selecting different sequences of the referencesub-group j.

The sequence group formed in the above method is described below throughexamples.

There are 3 sub-groups in total in this embodiment. The sequencecandidate collection includes Zadoff-Chu sequences whose lengths are 11,23 and 37 respectively, corresponding to three resource occupationmodes. If N_(p) ₁ =N₁=11 is selected, then there are 10 sequence groupsin total. By selecting the sequences that make the absolute value of(r_(m)/N_(m)−r₁/N₁) the smallest and including them into each sequencegroup, where each sub-group contains only one sequence and the sequenceis represented by a basic sequence index, the following table isgenerated:

TABLE 1 N₂ = 23 N₃ = 37 N₂ = 23 N₃ = 37 N₁ = 11 Basic Basic N₁ = 11Basic Basic Group Sequence Sequence Group Sequence Sequence Number KIndex r₂ Index r₃ Number K Index r₂ Index r₃ 1 2 3 6 13 20 2 4 7 7 15 243 6 10 8 17 27 4 8 13 9 19 30 5 10 17 10 21 34

The foregoing grouping method makes the absolute value ofr_(m)/N_(m)−r₁/N₁=(N₁r_(m)−N_(m)r₁)/(N₁N_(m)) the smallest, namely,makes the absolute value of N₁r_(m)−N_(m)r₁ the smallest. That is, themethod ensures high correlation between sequences. As verified, thecorrelation between the sequences in each sequence group in Table 1 isvery high.

In the foregoing embodiment, selection of the n sequences comes in twocircumstances:

Preferably, n is 1, namely, in the foregoing example, a sequence thatmakes (r_(m)/N_(m)−k/N₁) the smallest is selected and included into asub-group m.

Preferably, n is a natural number greater than 1, and the value of ndepends on the length difference between sub-group N_(m) and referencesub-group N₁. The sequences corresponding to several basic sequenceindexes near r_(m) that makes (r_(m)/N_(m)−k/N₁) the smallest areincluded into a sub-group. Generally, such sequences are n sequencesclosest to the minimum r_(m), where n depends on the length differencebetween N₁ and N_(m).

For example, if N_(m) is about 4×N₁, two r_(m)'s may be included intothe group. Generally, n=┌N_(m)/(2N_(i))┐ may be selected. In an example,n=└N_(m)/N₁┘ may be selected, where └z┘ is the maximum integer notgreater than z. In the sequence sub-group in this case, there may bemore than one sequence of a certain length. After such allocation in thesystem, when using the sequence, the user may select any of theallocated n sequences for transmitting, for example, select the sequencethat makes (r_(m)/N_(m)−k/N₁) the smallest, second smallest, and so on.

When two Zadoff-Chu sequences of different lengths are highlycorrelated, it is sure that |r_(m)/N_(m)−r₁/N₁| is relatively small. Inthe foregoing allocation method, it is ensured that the value of|r_(i)/N_(i)−r_(j)/N_(j)| between two sub-groups i,j of different groupsis great. Therefore, the sequences are little correlated betweendifferent groups, and the interference is low. Further, among thesequences of certain lengths, some may be selected for allocation, andthe remaining are not used in the system. This prevents the sequencesthe second most correlated with the sequences in the reference sub-groupfrom appearing in other sequence groups, and reduces stronginterference.

If the foregoing function d(a,b) is defined as |(a−b)modu m_(k,i)|,where modu m_(k,i) causes the value of the function d(a,b) after thisoperation to be included in (−m_(k,i)/2,m_(k,i)/2], and m_(k,i) is avariable determined by the group number k and sub-group number i, thenm_(k,i)=1/B, where B is a natural number, namely, m_(k,i)ε{1, ½, ⅓, ¼, .. . }.

The foregoing sequence allocation mode is described below, taking aZadoff-Chu sequence, namely, a_(r,N)(z), in the CAZAC sequence as anexample:

For the sequence group k=1, 2, . . . , the sub-group numbered p₁ isselected as a reference sub-group. The foregoing G_(k) is defined as

G_(k) = f_(p₁)({a_(w_(k), N_(p₁))(z)}_(z = −0, 1, …, N₁ − 1)) = w_(k)/N_(p₁),

N_(p) ₁ is the length of the reference sub-group sequence, and w_(k) isa basic sequence index of the sequence with a length of N_(p) ₁determined by the sequence group k. Particularly, if w_(k)=k isselected, then

G_(k) = f_(p₁)({a_(k, N_(p₁))}) = k/N_(p₁).

Therefore, the sequence that makes the d(ƒ_(p) ₁ (·), G_(k))=d(ƒ_(p) ₁(·), ƒ_(p) ₁ ({a_(k,N) _(p1) })) value the smallest in the sub-groupnumbered p₁ in the sequence group k is the {a_(k,N) _(p1) } sequencewith the index of r_(p1)=k and length of N_(p1). In this case,d(ƒ_(p1)(·), G_(k))=0.

The sequences in the sub-group i=q in the sequence group k are nsequences that have the length of N_(q) and make the|(r_(q)/N_(q)−k/N_(p1)) modu m_(k,q)| value the smallest, secondsmallest, and third smallest respectively, namely, n sequences that makethe d(ƒ_(p) ₁ (·), ƒ_(p) ₁ ({a_(k,N) _(p1) })) value the smallest.

It should be noted that the foregoing function d(a,b)=|(a−b) modum_(k,i)| may vary between different sequence groups, or differentsub-groups of the same sequence group. For example, all sub-groups ofone sequence group adopt a d(a,b) function, and all sub-groups ofanother sequence group adopt another d(a,b) function. Alternatively, onesub-group adopts a d(a,b) function, and another sub-group may adoptanother d(a,b) function. Specifically, m_(k,i) in the function hasdifferent values, which give rise to different measurement functions.

The sequence group formed in the foregoing method is described belowthrough examples.

There are 3 sub-groups in total in this embodiment. The sequencecandidate collection includes Zadoff-Chu sequences whose lengths are 31,47 and 59 respectively, corresponding to three resource occupationmodes. If N_(p1)=N₁=31 is selected, then there are 30 sequence groups intotal. By using m_(k,q) in Table 2 and selecting the sequences that make|(r_(q)/N_(q)−k/N₁) modu m_(k,q)| the smallest and including them intoeach sequence group, where each sub-group contains only one sequence andthe sequence is represented by a basic sequence index, Table 3 isgenerated:

TABLE 2 N₁ = 31 N₁ = 31 Group N₂ = 47 N₃ = 59 Group N₂ = 47 N₃ = 59Number K m_(k,2) m_(k,3) Number K m_(k,2) m_(k,3) 1 1/2 1 16 1/3 1/2 2 11 17 1/4 1/2 3 1/2 1/3 18 1/3 1 4 1 1/2 19 1 1 5 1/2 1/2 20 1/3 1 6 11/2 21 1 1 7 1/2 1/3 22 1/3 1 8 1 1 23 1 1 9 1/3 1 24 1/2 1/3 10 1 1 251 1/2 11 1/3 1 26 1/2 1/2 12 1 1 27 1 1/2 13 1/3 1 28 1/2 1/3 14 1/4 1/229 1 1 15 1/3 1/2 30 1/2 1

TABLE 3 N₂ = 47 N₃ = 59 N₂ = 47 N₃ = 59 N₁ = 31 Basic Basic N₁ = 31Basic Basic Group Sequence Sequence Group Sequence Sequence Number KIndex r₂ Index r₃ Number K Index r₂ Index r₃ 1 25 2 16 40 1 2 3 4 17 143 3 28 45 18 43 34 4 6 37 19 29 36 5 31 39 20 46 38 6 9 41 21 32 40 7 3433 22 2 42 8 12 15 23 35 44 9 45 17 24 13 26 10 15 19 25 38 18 11 1 2126 16 20 12 18 23 27 41 22 13 4 25 28 19 14 14 33 56 29 44 55 15 7 58 3022 57

The following grouping method makes |(r_(q)/N_(q)−k/N₁) modu m_(k,q)|smallest. As verified, all the sequences in Table 3 are the sequencesthe most correlated with the sequences in the reference sub-group of thesame sequence group. Therefore, the correlation of the sequences betweendifferent groups is further reduced, and the inter-group interference isweaker.

When the number of sub-carriers that bear the sequence in the cell isnot a prime number, it is necessary to select the sequence whose lengthis equal to the prime number around the number of sub-carriers, and thedesired sequence is obtained through sequence segmentation or cyclicextension of the sequence before being transmitted.

The following description takes cyclic extension as an example. In thisembodiment, there are quantities of sub-carriers that bear thesequences: 36, 48, and 60.

The sequences with a length of the maximum prime number less than thequantity of sub-carriers, namely, the Zadoff-Chu sequences correspondingto the lengths 31, 47 and 59, are selected, and the desired sequencesare obtained through cyclic extension of such sequences. If N_(p) ₁=N₁=31 is selected, then there are 30 sequence groups in total. By usingm_(k,q) in Table 4 and selecting the sequences that make|(r_(q)/N_(q)−k/N₁) modu m_(k,q)| the smallest and including them intoeach sequence group, where each sub-group contains only one sequence andthe sequence is represented by a basic sequence index, Table 5 isgenerated:

TABLE 4 N₁ = 31 N₁ = 31 N₂ = 47 Group N₂ = 47 N₃ = 59 Group N₃ = 59m_(k,2) Number K m_(k,2) m_(k,3) Number K m_(k,3) 1 1/2 1 16 1/3 1/2 2 11 17 1 1/3 3 1/2 1/3 18 1/3 1/3 4 1 1/2 19 1 1 5 1/2 1/2 20 1/3 1 6 11/2 21 1 1 7 1/3 1/3 22 1/3 1 8 1 1 23 1 1 9 1/3 1 24 1/3 1/3 10 1 1 251 1/2 11 1/3 1 26 1/2 1/2 12 1 1 27 1 1/2 13 1/3 1/3 28 1/2 1/3 14 1 1/329 1 1 15 1/3 1/2 30 1/2 1

TABLE 5 N₂ = 47 N₃ = 59 N₂ = 47 N₃ = 59 N₁ = 31 Basic Basic N₁ = 31Basic Basic Group Sequence Sequence Group Sequence Sequence Number KIndex r₂ Index r₃ Number K Index r₂ Index r₃ 1 25 2 16 40 1 2 3 4 17 2652 3 28 45 18 43 54 4 6 37 19 29 36 5 31 39 20 46 38 6 9 41 21 32 40 742 33 22 2 42 8 12 15 23 35 44 9 45 17 24 5 26 10 15 19 25 38 18 11 1 2126 16 20 12 18 23 27 41 22 13 4 5 28 19 14 14 21 7 29 44 55 15 7 58 3022 57

The following grouping method makes |(r_(q)/N_(q)−k/N₁) modu m_(k,q)|the smallest. As verified, all the sequences in Table 5 are thesequences the most correlated with the sequences in the reference lengthof the same sequence group. Therefore, the correlation of sequencesbetween different groups is further reduced, and the inter-groupinterference is weaker.

The specific value of m_(k,q) may be: if N_(q)≧L_(r), then m_(k,q)=1,where N_(q) is the sequence length of the sub-group q, and L_(r) isdetermined by the reference sub-group sequence length N_(p) ₁ .Specifically, for N_(p) ₁ =N₁=31, L_(r)=139. If N_(q)=139 or above, thenm_(k,q)=1. After cyclic extension of the sequence, L_(r)=191. Therefore,when N_(q)=191 or above, m_(k,q)=1.

In the foregoing embodiment, selection of the n sequences comes in twocircumstances:

Preferably, n is 1, namely, in the foregoing example, a sequence thatmakes |(r_(q)/N_(q)−k/N₁) modu m_(k,q)| the smallest is selected andincluded into the sub-group q.

Preferably, n is a natural number greater than 1, and the value of ndepends on the length difference between sub-group N_(q) and referencesub-group N₁. The sequences corresponding to several basic sequenceindexes near r_(q) that makes |(r_(q)/N_(q)−k/N₁) modu m_(k,q)| thesmallest are included into a sub-group. Generally, such sequences are nsequences closest to the minimum r_(q), where n depends on the lengthdifference between N₁,N_(q). For example, if N_(q) is about 4×N₁, twor_(q)'s may be included into the group. Generally, n=|N_(q)/(2N₁)| maybe selected, where ┌z┐ is the minimum integer greater than z. In anotherexample, n=└N_(q)/N₁┘ may be selected, where ┌z┐ is the maximum integernot greater than z. In the sequence sub-group in this case, there may bemore than one sequence of a certain length. After such allocation in thesystem, when using the sequence, the user may select any of theallocated n sequences for transmitting, for example, select r_(q)=ƒ thatmakes |(r_(q)/N_(q)−k/N₁) modu m_(k,q)| the smallest, then the fewer nsequences are ƒ±1, ƒ±2 . . . . The transmitter and the receiver mayobtain the data through calculation in this way rather than store thedata.

When two Zadoff-Chu sequences of different lengths are highlycorrelated, it is sure that |(r_(q)/N_(q)−r₁/N₁) modu m_(r) _(1,q) | isrelatively small. In the foregoing allocation method, it is ensured thatthe value of i,j between two sub-groups |(r_(i)/N_(i)−r_(j)/N_(j)) modum_(r) _(j) _(,i)| of different groups is great. Therefore, the sequencesare little correlated between different groups, and the interference islow. Further, among the sequences of certain lengths, some may beselected for allocation, and the remaining are not used in the system.This prevents the sequences the second most correlated with thesequences in the reference sub-group from appearing in other sequencegroups, and reduces strong interference between groups.

In other embodiments, the definition of the foregoing function d(a,b)may also be

$\mspace{20mu} {{d\left( {a,b} \right)} = \left\{ {\begin{matrix}{{{a - b}},} & {{{when}\mspace{14mu} u} \leq \left( {a - b} \right) \leq v} \\{{infinity},} & {others}\end{matrix},{{{or}{d\left( {a,b} \right)}} = \left\{ {\begin{matrix}{{{\left( {a - b} \right){modu}\mspace{14mu} m_{k,i}}},} & {{{when}\mspace{14mu} u} \leq {\left( {a - b} \right){modu}\mspace{14mu} m_{k,i}} \leq v} \\{{infinity},} & {others}\end{matrix}.} \right.}} \right.}$

The infinity in the definition of the d(a,b) function filters outcertain sequences, and ensures low correlation between different groups.

It should be noted that the foregoing function

${d\left( {a,b} \right)} = \left\{ {\begin{matrix}{{{a - b}},} & {{{when}\mspace{14mu} u} \leq \left( {a - b} \right) \leq v} \\{{infinity},} & {others}\end{matrix},{{{or}{d\left( {a,b} \right)}} = \left\{ \begin{matrix}{{{\left( {a - b} \right){modu}\mspace{14mu} m_{k,i}}},} & {{{when}\mspace{14mu} u} \leq {\left( {a - b} \right){modu}\mspace{14mu} m_{k,i}} \leq v} \\{{infinity},} & {others}\end{matrix} \right.}} \right.$

may vary between different sequence groups, or different sub-groups ofthe same sequence group. For example, all sub-groups of one sequencegroup adopt a d(a,b) function, and all sub-groups of another sequencegroup adopt another d(a,b) function. Alternatively, one sub-group adoptsa d(a,b) function, and another sub-group may adopt another d(a,b)function.

Specifically, u,v in the function has different values, which give riseto different measurement functions. For example, u=0,v=+∞, or u=−∞, v=0,or u=−1/(2×11)+1/(23×4), v=1/(2×11)−1/(23×4), or u=a,v=b, where a,bdepend on the sequence group k and sub-group i, and so on.

Specifically, in the foregoing embodiment of ƒ_(i):{a_(r) _(i) _(,N)_(i) (z)}_(z=0, 1, 2, . . . , N) _(i) ⁻¹→r_(i)/N_(i),

${{if}\mspace{14mu} {d\left( {a,b} \right)}} = \left\{ {\begin{matrix}{{{a - b}},} & {{{when}\mspace{14mu} u} \leq \left( {a - b} \right) \leq v} \\{{infinity},} & {others}\end{matrix},} \right.$

this embodiment is: selecting the sequences that meetu≦(r_(i)/N_(i)−k/N_(p) _(i) )≦v and including them into each sequencegroup; |r_(i)/N_(i)−r_(j)/N_(j)|>1/C_(i) is met between any twosequences of different sequence groups, where N_(i)<N_(j), as detailedbelow:

First, u=0,v=+∞ or u=−∞,v=0, namely, the sequences that make the valuethe smallest in a single direction. For the positive direction, it isequivalent to selecting the sequences that meet (r_(m)/N_(m)−k/N_(p) ₁)≧0; for the negative direction, it is equivalent to selecting thesequences that meet (k/N_(p) ₁ −r_(m)/N_(m))≧0. For example, if thesub-group length is N_(m), the positive result closest to k/N_(p) ₁ isr_(m) with the difference of 0.036, and the negative result closest tok/N_(p) ₁ is r_(m)′ with the difference of −0.025. The one the mostcorrelated with the r_(p) ₁ =k sequence of a length of N_(p) ₁ isr_(m)′. If the system specifies that the sequence in the positivedirection of (r_(m)/N_(m)−k/N_(p) ₁ ) needs to be selected, r_(m) isselected. The benefit is: after the sequences of various lengths arecompared with k/N_(p) ₁ , the difference between the function values,namely, |r_(i)/N_(i)−r_(j)/N_(j)|, is smaller.

Secondly, u=−1/(2N_(p) ₁ )+1/(4N_(p) ₂ ) and v=1/(2N_(p) ₁ )−1/(4N_(p) ₂) may be selected. The length (N_(p) ₁ ) of the reference sequence isthe shortest sequence length and N_(p) ₂ is the sequence length onlygreater than N_(p) ₁ . Here is an example:

In this embodiment, there are 4 sub-groups in total. The candidatesequence collections contain Zadoff-Chu sequences with N₁=11, N₂=23, N₃,and N₄=47 respectively. By selecting the sequences that meet|r_(i)/N_(i)−k/N₁|<1/(2N₁)−1/(4N₂), namely,|r_(i)/N_(i)−k/N₁|<1/(2×11)−1/(4×23) and including them into thesub-groups of each sequence group, the following table is generated,where the sequence is represented by a basic sequence index:

TABLE 6 N₂ = 23 N₃ = 37 N₄ = 47 N₁ = 11 Basic Basic Basic Group SequenceSequence Sequence Number K Index r₂ Index r₃ Index r₄  1 2 3, 4 3, 4, 5 2 4 6, 7, 8 7, 8, 9, 10  3 6, 7 9, 10, 11 12, 13, 14  4 8, 9 13, 14 16,17, 18  5 10, 11 16, 17, 18 20, 21, 22  6 12, 13 19, 20, 21 25, 26, 27 7 14, 15 23, 24 29, 30, 31  8 16, 17 26, 27, 28 33, 34, 35  9 19 29,30, 31 37, 38, 39, 40 10 21 33, 34 42, 43, 44

In table 6, |r_(i)/N_(i)−r_(j)/N_(j)|>1/(2N_(i)) is met between any twosequences of different sequence groups, where N_(i)<N_(j). In this way,the correlation between the two sequences is relatively lower.

Thirdly, for different sequence groups k and different sub-groups i inthe same sequence group, u,v may differ.

The shortest sequence is selected as a reference sequence. Therefore,N_(p) ₁ represents the length of the shortest sequence, and N_(p) _(L)represents the length of the longest sequence; the sequence group thatincludes the basic sequence with a length of N_(p) ₁ and an index of 1is numbered “q₁”; the sequence group that includes the basic sequencewith a length of N_(p) ₁ and an index of N_(p) ₁ −1 is numbered “q_(N)_(p1) ⁻¹”; the sequence group that includes the basic sequence with alength of N_(p) ₁ and an index of k is numbered “q_(k)”; the sequencegroup that includes the basic sequence with a length of N_(p) ₁ and anindex of k+1 is numbered “q_(k+1)”; the sub-group that includes thebasic sequence with a length of N_(p) ₁ is numbered “p₁”; the sub-groupthat includes the basic sequence with a length of N_(p) _(m) is numbered“p_(m)”; the sub-group that includes the basic sequence with a length ofN_(p) _(i−1) is numbered “p_(i−1)”; and the sub-group that includes thebasic sequence with a length of N_(p) ₁ is numbered “p_(i)”, where N_(p)_(i−1) <N_(p) _(i) .

Step 1001: For the sub-group P of the sequence group q₁, u_(q) ₁ _(p) ₁=−1/(2N_(p) ₁ )+δ_(u), where 1/N_(p) _(L) −1/N_(p) ₁ +1/(2N_(p) ₁)≦δ_(u)<½(N_(p) ₁ ).

v_(q) _(k) _(,p) ₁ of the sub-group p₁ of the sequence group q_(k) andu_(q) _(k+1) _(p) ₁ of the sub-group p₁ of the sequence group q_(k+1)(k−1, . . . N_(p) ₁ −2) are:

v_(p) _(k) _(,p) ₁ =1/D u_(q) _(k+1) _(p) ₁ =−1/D where 1/D≦1/(2N_(p) ₁).

Step 1002: As shown in FIG. 3, v_(q) _(k) _(,p) _(i) of the sub-groupp_(i) of the sequence group q_(k) and u_(q) _(k+1) _(,p) _(i) of thesub-group p_(i) of the sequence group q_(k+1) (k=1, . . . , N_(p) ₁ −2,iεS) are:

right_(q) _(k) _(,p) _(i−1) =v_(q) _(k) _(,p) _(i−1) +k/N_(p) ₁ ,left_(q) _(k+1) _(,p) _(i−1) =u_(q) _(k+1) _(,p) _(i−1) +(k+1)/N_(p) ₁

For the basic sequence with a length of N_(p) _(i−1) , depending on thevalue of r_(p) _(i−1) , r_(q) _(k+1) _(,p) _(i−1) that meets r_(p)_(i−1) /N_(p) _(i−1) left_(q) _(k+1) _(,p) _(i−1) ≧0 and minimum |r_(p)_(i−1) /N_(p) _(i−1) −left_(q) _(k+1) _(,p) _(i−1) | is obtained,namely, the obtained basic sequence r_(q) _(k+1) _(,p) _(i−1) isincluded in the sequence group q_(k+1), has a length of N_(p) _(i−1) andis closest to the left border (left_(q) _(k+1) _(,p) _(i−1) ) of thesequence group q_(k+1).

If r_(q) _(k+1) _(,p) _(i−1) /N_(p) _(i−1) −1/C_(p) _(i−1) −right_(q)_(k) _(,p) _(i−1) ≦0, namely, r_(q) _(k−) _(,p) _(i−1) /N_(p) _(i−1)−1/C_(p) _(i−1) is less than the right border (right_(q) _(k) _(,p)_(i−1) ) of the sequence group q_(k), then v_(q) _(k) _(p) ₁ =v_(q) _(k)_(,p) _(i−1) +r_(q) _(k+1) _(,p) _(i−1) /N_(p) _(i−1) −1/C_(p) _(i−1)−right_(q) _(k) _(,p) _(i−1) , to ensure low cross correlation betweenthe sequence group q_(k) and its adjacent sequence group q_(k+1); ifr_(p) _(k+1) _(,p) _(i−1) /N_(p) _(i−1) −1/C_(p) _(i−1) −right_(q) _(k)_(, p) _(i−1) >0 namely, is greater than r_(p) _(k+1) _(,p) _(i−1)/N_(p) _(i−1) −1/C_(p) _(i−1) the right border (right_(q) _(k) _(, p)_(i−1) ) of the sequence group q_(k), then v_(q) _(k) _(,p) _(i) =v_(q)_(k) _(,p) _(i−1) .

For the basic sequence with a length of N_(p) _(i−1) , depending on thevalue of r_(p) _(i−1) , r_(p) _(k) _(,p) _(i−1) that meets r_(p) _(i−1)/N_(p) _(i−1) −right_(q) _(k) _(,p) _(i−1) ≦0 and minimum |r_(p) _(i−1)/N_(p) _(i−1) −right_(q) _(k) _(,p) _(i−1) | is obtained, namely, theobtained basic sequence q_(k) is included in the sequence group N_(p)_(i−1) , has a length of q_(k) and is closest to the right border(right_(q) _(k) _(,p) _(i−1) ) of the sequence group r_(q) _(k) _(,p)_(i−1) .

If r_(q) _(k) _(,p) _(i−1) /N_(p) _(i−1) +1/C_(p) _(i−1) −left_(q)_(k+1) _(,p) _(i−1) ≧0, namely, r_(q) _(k) _(, p) _(i−1) /N_(p) _(i−)1/C_(p) _(i−1) is greater than the left border (q_(k+1)) of the sequencegroup left_(q) _(k+1) _(,p) _(i−1) , then

u_(q_(k + 1), p_(i)) = u_(q_(k + 1), p_(i − 1))/N_(p_(i − 1)) + 1/C_(p_(i − 1)) − left_(q_(k + 1)), p_(i − 1),

to ensure low cross correlation between the sequence group q_(k) and itsadjacent sequence group q_(k+1); if r_(q) _(k) _(,p) _(i−1) /N_(p)_(i−1) +1/C_(p) _(i−1) −left_(q) _(k+1) _(,p) _(i−1) <0, namely, r_(q)_(k) _(, p) _(i−1) /N_(p) _(i−) 1/C_(p) _(i−1) is less than the leftborder (q_(k+1)) of the sequence group left_(q) _(k+1) _(,p) _(i−1) ,then u_(q) _(k+1) _(,p) _(i) =u_(q) _(k+1) _(,p) _(i−1) .

q_(N) _(p1) ⁻¹ of the sub-group p_(i) of the sequence group

v_(q_(N_(p₁) − 1), p_(i))

and q₁ of the sub-group p_(i) of the sequence group u_(q) _(q) _(,p)_(i) (iεS) are:

right_(q_(N_(p 1) − 1, p_(i − 1))) = v_(q_(N_(p 1) − 1, p_(i − 1))) + (N_(p₁) − 1)/N_(p₁), left_(q₁, p_(i − 1)) = u_(q₁p_(i − 1)) + 1/N_(p₁)right_(q_(N_(p 1) − 1, p_(i − 1))^(′)) = v_(q_(N_(p 1) − 1, p_(i − 1))) − 1/N_(p₁), left_(q₁, p_(i − 1))^(′) = u_(q₁, p_(i − 1)) + (N_(p₁) + 1)/N_(p₁)

For the basic sequence with a length of N_(p) _(i−1) , depending on thevalue of r_(p) _(i−1) , r_(q) ₁ _(,p) _(i−1) that meets r_(p) _(i−1)/N_(p) _(i−1) −left_(q) ₁ _(,p) _(i−1) ≧0 and minimum |r_(p) _(i−1)/N_(p) _(i−1) −left_(q) ₁ _(,p) _(i−1) | is obtained;

  If  r_(q₁, p_(i − 1))/N_(p_(i − 1)) − 1/C_(p_(i − 1)) − right_(q_(N_(p 1) − 1, p_(i − 1))^(′)) ≤ 0, thenv_(q_(N_(p 1) − 1, p_(i))) = v_(q_(N_(p 1) − 1, p_(i − 1))) + r_(q₁, p_(i − 1))/N_(p_(i − 1)) − 1/C_(p_(i − 1)) − right_(q_(N_(p 1) − 1, p_(i − 1))^(′)); if  r_(q₁, p_(i − 1))/N_(p_(i − 1)) − 1/C_(p_(i − 1)) − right_(q_(N_(p 1) − 1, p_(i − 1))^(′)) > 0, then  v_(q_(N_(p 1) − 1, p_(i))) = v_(q_(N_(p 1) − 1, p_(i − 1)));

For the basic sequence with a length of N_(p) _(i−1) , depending on thevalue of r_(p) _(i−1) ,

r_(q_(N_(p 1) − 1, p_(i − 1)))

that meets

r_(p_(i − 1))/N_(p_(i − 1)) − right_(q_(N_(p 1) − 1, p_(i − 1))) ≤ 0

and minimum

r_(p_(i − 1))/N_(p_(i − 1)) − right_(q_(N_(p 1) − 1, p_(i − 1)))

is obtained

If  r_(q_(N_(p 1) − 1, p_(i − 1)))/N_(p_(i − 1)) + 1/C_(p_(i − 1)) − left_(q₁, p_(i − 1))^(′) ≥ 0, thenu_(q₁, p_(i)) = u_(q₁, p_(i − 1)) + r_(q_(N_(p 1) − 1, p_(i − 1)))/N_(p_(i − 1)) + 1/C_(p_(i − 1)) − left_(q₁, p_(i − 1))^(′); ifr_(q_(N_(p 1) − 1, p_(i − 1)))/N_(p_(i − 1)) + 1/C_(p_(i − 1)) − left_(q₁, p_(i − 1))^(′) < 0, then  u_(q₁, p_(i)) = u_(q₁, p_(i − 1));

Particularly, C_(p) _(i−1) =2N_(p) _(i−1) .

Step 1003: u_(q) _(k) _(,p) _(i) and v_(q) _(k) _(,p) _(i) of thesub-group p_(i) in the sequence group q_(k) (k=1, . . . , N_(p) ₁ −1,iεI−S) are:

-   -   u_(q) _(k) _(,p) _(i) =u_(q) _(k) _(,p) _(m) and v_(q) _(k)        _(,p) _(i) =v_(q) _(k) _(,p) _(m) , respectively

where I and S are two index collections; in the collection I={2, 3 . . ., L)}, L is the quantity of sequence lengths in a candidate sequencecollection, and the collection S is the collection I or a sub-collectionof the collection I, and m is an element with the maximum value in thecollection S.

In the following example, δ_(u)=0, δ_(v)=0 D=2N_(p) _(i) , C_(p) _(i−1)=2N_(p) _(i−1) , q_(k)=k and p_(i)=i.

Example 1

In this example, there are 4 sub-groups in total. The candidate sequencecollection contains the Zadoff-Chu are sequences with N₁=11, N₂=23,N₃=37, and N₄=47 respectively. Taking the fourth sequence group as anexample (namely, k=4), v_(4,i) and u_(5,i)iε{1, 2, 3, 4} are obtainedthrough step 1101, specifically:

For the sub-group 1, v_(4,1)=1/(2×11) u_(5,1)=−1/(2×11).

For the sub-group 2, right_(4,1)=v_(4,1)+4/11=1/(2×11)+4/11left_(5,1)=u_(5,1)+5/11=−1/(2×11)+5/11; because no r_(5,1) or r_(4,1)compliant with the conditions exists, v_(4,2)=v_(4,1), namely,v_(4,2)=1/(2×11); u_(5,2)=u_(5,1), namely, u_(5,2)=−1/(2×11).

For the sub-group 3, right_(4,2)=v_(4,2)+4/11=1/(2×11)+4/11left_(5,2)=u_(5,2)+5/11=−1/(2×11)+5/11.

For N₂=23, when r₂ varies, if r_(5,2)=10, then r_(5,2)/N₂−left_(5,2)>0and |r_(5,2)/N₂−left_(5,1)| is the minimum value; becauser_(5,2)/N₂−½(N₂)−right_(4,2)>0, v_(4,3)=v_(4,2), namely,v_(4,3)=1/(2×11).

For N₂=23, when r₂ varies, if r_(4,2)=9, then r_(4,2)/N₂−right_(4,2)<0and |r_(4,2)/N₂−right_(4,2)| is the minimum value; becauser_(4,2)/N₂+1/(2N₂)−left_(5,2)>0

$\begin{matrix}{u_{5,3} = {u_{5,2} + {r_{4,2}/N_{2}} + {1/\left( {2\; N_{2}} \right)} - {left}_{5,2}}} \\{= {{{- 1}/\left( {2 \times 11} \right)} + {9/23} + {1/\left( {2 \times 23} \right)} - \left( {{{- 1}/\left( {2 \times 11} \right)} + {5/11}} \right)}} \\{= {{- 21}/{\left( {2 \times 11 \times 23} \right).}}}\end{matrix}$

For the sub-group 4, right_(4,3)=v_(4,3)+4/11=1/(2×11)+4/11left_(5,3)=u_(5,3)+5/11=−21/(2×11×23)+5/11.

For N₃=37, when r₃ varies, if r_(5,3)=16, then r_(5,3)/N₃−left_(5,3)>0and |r_(5,3)/N₃−left_(5,3)| is the minimum value; becauser_(5,3)/N₃−1/(2N₃)−right_(4,3)>0 v_(4,4)=v_(4,3), namely,v_(4,4)=1/(2×11).

For N₃=37, when r₃ varies, if r_(4,3)=15, then r_(4,3)/N₃−right_(4,3)<0and |r_(4,3)/N₃−right_(4,3)| is the minimum value; becauser_(4,3)/N₃+1/(2N₃)−left_(5,3)>0,

$\begin{matrix}{u_{5,4} = {u_{5,3} + {r_{4,3}/N_{3}} + {1/\left( {2\; N_{3}} \right)} - {left}_{5,3}}} \\{= {{{- 21}/\left( {2 \times 11 \times 23} \right)} + {15/37} + {1/\left( {2 \times 37} \right)} -}} \\{\left( {{{- 21}/\left( {2 \times 11 \times 23} \right)} + {5/11}} \right)} \\{= {{- 29}/{\left( {2 \times 11 \times 37} \right).}}}\end{matrix}$

By analogy, u and v of all sub-groups of all sequence groups areobtained, and the following table is generated:

TABLE 7 Sub-Group i Group Number k 1 2 3 4 1 u_(1,1) = −1/(2 × 11)u_(1,2) = −1/(2 × 11) u_(1,3) = −1/(2 × 11) u_(1,4) = −1/(2 × 11)v_(1,1) = 1/(2 × 11) v_(1,2) = 1/(2 × 11) v_(1,3) = 1/(2 × 11) v_(1,4) =1/(2 × 11) 2 u_(2,1) = −1/(2 × 11) u_(2,2) = −1/(2 × 11) u_(2,3) =−15/(2 × 11 × 23) u_(2,4) = −15/(2 × 11 × 23) v_(2,1) = 1/(2 × 11)v_(2,2) = 1/(2 × 11) v_(2,3) = 1/(2 × 11 ) v_(2,4) = 1/(2 × 11) 3u_(3,1) = −1/(2 × 11) u_(3,2) = −1/(2 × 11) u_(3,3) = −17/(2 × 11 × 23)u_(3,4) = −17/(2 × 11 × 23) v_(3,1) = 1/(2 × 11) v_(3,2) = 1/(2 × 11)v_(3,3) = 1/(2 × 11) v_(3,4) = 1/(2 × 11) 4 u_(4,1) = −1/(2 × 11)u_(4,2) = −1/(2 × 11) u_(4,3) = −19/(2 × 11 × 23) u_(4,4) = −19/(2 × 11× 23) v_(4,1) = 1/(2 × 11) v_(4,2) = 1/(2 × 11) v_(4,3) = 1/(2 × 11)v_(4,4) = 1/(2 × 11) 5 u_(5,1) = −1/(2 × 11) u_(5,2) = −1/(2 × 11)u_(5,3) = −21/(2 × 11 × 23) u_(5,4) = −29/(2 × 11 × 37) v_(5,1) = 1/(2 ×11) v_(5,2) = 1/(2 × 11) v_(5,3) = 1/(2 × 11) v_(5,4) = 1/(2 × 11) 6u_(6,1) = −1/(2 × 11) u_(6,2) = −1/(2 × 11) u_(6,3) = −1/(2 × 11)u_(6,4) = −1/(2 × 11) v_(6,1) = 1/(2 × 11) v_(6,2) = 1/(2 × 11) v_(6,3)= 21/(2 × 11 × 23) v_(6,4) = 29/(2 × 11 × 37) 7 u_(7,1) = −1/(2 × 11)u_(7,2) = −1/(2 × 11) u_(7,3) = −1/(2 × 11) u_(7,4) = −1/(2 × 11)v_(7,1) = 1/(2 × 11) v_(7,2) = 1/(2 × 11) v_(7,3) = 19/(2 × 11 × 23)v_(7,4) = 19/(2 × 11 × 23) 8 u_(8,1) = −1/(2 × 11) u_(8,2) = −1/(2 × 11)u_(8,3) = −1/(2 × 11) u_(8,4) = −1/(2 × 11) v_(8,1) = 1/(2 × 11) v_(8,2)= 1/(2 × 11) v_(8,3) = 17/(2 × 11 × 23) v_(8,4) = 17/(2 × 11 × 23) 9u_(9,1) = −1/(2 × 11) u_(9,2) = −1/(2 × 11) u_(9,3) = −1/(2 × 11)u_(9,4) = −1/(2 × 11) v_(9,1) = 1/(2 × 11) v_(9,2) = 1/(2 × 11) v_(9,3)= 15/(2 × 11 × 23) v_(9,4) = 15/(2 × 11 × 23) 10 u_(10,1) = −1/(2 × 11)u_(10,2) = −1/(2 × 11) u_(10,3) = −1/(2 × 11) u_(10,4) = −1/(2 × 11)v_(10,1) = 1/(2 × 11) v_(10,2) = 1/(2 × 11) v_(10,3) = 1/(2 × 11)v_(10,4) = 1/(2 × 11)

Step 1102: The sequences that meet u_(k,i)≦(r_(i)/N_(i)−k/N₁)≦v_(k,i)are selected and included into the sub-group i of the sequence group k,where the sequence is represented by a basic sequence index. Thus thefollowing table is generated:

TABLE 8 N₂ = 23 N₃ = 37 N₄ = 47 N₁ = 11 Basic Basic Basic Group SequenceSequence Sequence Number K Index r₂ Index r₃ Index r₄  1 2, 3 2, 3, 4, 53, 4, 5, 6  2 4, 5 6, 7, 8 8, 9, 10  3 6, 7 9, 10, 11 12, 13, 14  4 8, 913, 14, 15 16, 17, 18, 19  5 10, 11 16, 17, 18 20, 21, 22, 23  6 12, 1319, 20, 21 24, 25, 26, 27  7 14, 15 22, 23, 24 28, 29, 30, 31  8 16, 1726, 27, 28 33, 34, 35  9 18, 19 29, 30, 31 37, 38, 39 10 20, 21 32, 33,34, 35 41, 42, 43, 44

Example 2

If the sequence group contains more sub-groups, after u and v arecalculated to a certain sub-group, u and v of the sub-groups of longersequences do not change any more. For example, if the system bandwidthis 5 Mbps, the sequence lengths include: N₁=11, N₂=23, N₃=37, N₄=47,N₅=59, N₆=71, N₇=97, N₈=107, N₉=113, N₁₀=139, N₁₁=179, N₁₂=191, N₁₃=211,N₁₄=239, N₁₅=283, and N₁₆=293. Taking the fourth sequence group as anexample, namely, k=4, v_(4,i) and u_(5,1)iε{1, 2, 3, . . . , 16} areobtained in the following way:

For the sub-group 1, v_(4,1)=1/(2×11), and u_(5,1)=−1/(2×11).

For the sub-group 2, right_(4,1)=v_(4,1)+4/11=1/(2×11)+4/11,left_(5,1)=u_(5,1)+5/11=−1/(2×11)+5/11; because no r_(5,1) or r_(4,1)compliant with the conditions exists, v_(4,2)=v_(4,1) namely,v_(4,2)=1/(2×11); u_(5,2)=u_(5,1), namely, u_(5,2)=−1/(2×11).

For the sub-group 3, right_(4,2)=v_(4,2)+4/11=1/(2×11)+4/11, andleft_(5,2)=u_(5,2)+5/11=−1/(2×11)+5/11.

For N₂=23, when r₂ varies, if r_(5,2)=10, then r_(5,2)/N₂−left_(5,2)>0and |r_(5,2)/N₂−left_(5,2)| is the minimum value; becauser_(5,2)/N₂−½(N₂)−right_(4,2)>0, v_(4,3)=v_(4,2) namely,v_(4,3)=1/(2×11).

For N₂=23, when r₂ varies, if r_(4,2)=9, then r_(4,2)/N₂−right_(4,2)<0and |r_(4,2)/N₂−right_(4,2)| is the minimum value; becauser_(4,2)/N₂+1/(2N₂)−left_(5,2)>0,

$\begin{matrix}{u_{5,3} = {u_{5,2} + {r_{4,2}/N_{2}} + {1/\left( {2\; N_{2}} \right)} - {left}_{5,2}}} \\{= {{{- 1}/\left( {2 \times 11} \right)} + {9/23} + {1/\left( {2 \times 23} \right)} - \left( {{{- 1}/\left( {2 \times 11} \right)} + {5/11}} \right)}} \\{= {{- 21}/{\left( {2 \times 11 \times 23} \right).}}}\end{matrix}$

For the sub-group 4, right_(4,3)=v_(4,3)+4/11=1/(2×11)+4/11, andleft_(5,3)=u_(5,3)+5/11=−21/(2×11×23)+5/11.

For N₃=37, when r₃ varies, if r_(5,3)=16, then r_(5,3)/N₃−left_(5,3)>0and |r_(5,3)/N₃−left_(5,3)| is the minimum value; becauser_(5,3)/N₃−1/(2N)−right_(4,3)>0, v_(4,4)=v_(4,3), namely,v_(4,4)=1/(2×11).

For N₃=37, when r₃ varies, if r_(4,3)=15, then r_(4,3)/N₃−right_(4,3)<0and |r_(4,3)/N₃−right_(4,3)| is the minimum value; becauser_(4,3)/N₃+1/(2N₃)−left_(5,3)>0,

$\begin{matrix}{u_{5,4} = {u_{5,3} + {r_{4,3}/N_{3}} + {1/\left( {2\; N_{3}} \right)} - {left}_{5,3}}} \\{= {{{- 21}/\left( {2 \times 11 \times 23} \right)} + {15/37} + {1/\left( {2 \times 37} \right)} -}} \\{\left( {{{- 21}/\left( {2 \times 11 \times 23} \right)} + {5/11}} \right)} \\{= {{- 29}/\left( {2 \times 11 \times 37} \right)}}\end{matrix}$

For the sub-group 5, v_(4,5)=v_(4,4), namely, v_(4,5)=1/(2×11);u_(5,5)=u_(5,4), namely, u_(5,5)=−29/(2×11×37).

For the sub-group 6, v_(4,6)=v_(4,5), namely, v_(4,6)=1/(2×11);u_(5,6)=u_(5,5), namely, u_(5,6)=−29/(2×11×37).

For the sub-group 7, v_(4,7)=v_(4,6), namely, v_(4,7)=1/(2×11);u_(5,7)=u_(5,6), namely, u_(5,7)=−29/(2×11×37).

Further calculation reveals that: for sub-groups 8, 9, 10, . . . , 16,the values of u and v do not change any more.

By analogy, u and v of all sub-groups of other sequence groups may beobtained. Calculation reveals that: for any sub-group i of the sequencegroup 5, v_(5,i)=1/(2×11). Based on the foregoing calculation, thesequences that meet u_(5,i)≦(r_(i)/N_(i)−5/N₁)≦v_(5,i) are selected andincluded into the sub-group i of the sequence group 5, where thesequence is represented by a basic sequence index. Thus the followingtable is generated:

TABLE 9 N₁ = 11 group number k 5 N₂ = 23 basic sequence index r₂ 10, 11N₃ = 37 basic sequence index r₃ 16, 17, 18 N₄ = 47 basic sequence indexr₄ 20, 21, 22, 23 N₅ = 59 basic sequence index r₅ 25, 26, 27, 28, 29 N₆= 71 basic sequence index r₆ 30, 31, 32, 33, 34, 35 N₇ = 97 basicsequence index r₇ 41, 42, 43, 44, 45, 46, 47, 48 N₈ = 107 basic sequenceindex r₈ 45, 46, 47, 48, 49, 50, 51, 52, 53 N₉ = 113 basic sequenceindex r₉ 48, 49, 50, 51, 52, 53, 54, 55, 56 N₁₀ = 139 basic sequenceindex r₁₀ 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69 N₁₁ = 179 basicsequence index r₁₁ 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87,88, 89 N₁₂ = 191 basic sequence index r₁₂ 81, 82, 83, 84, 85, 86, 87,88, 89, 90, 91, 92, 93, 94, 95 N₁₃ = 211 basic sequence index r₁₃ 89,90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105 N₁₄= 239 basic sequence index r₁₄ 101, 102, 103, 104, 105, 106, 107, 108,109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119 N₁₅ = 283 basicsequence index r₁₅ 119, 120, 121, 123, 124, 125, 126, 127, 128, 129,130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141 N₁₆ = 293basic sequence index r₁₆ 123, 124, 125, 126, 127, 128, 129, 130, 131,132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145,146

The foregoing calculation of u_(k,i), v_(k,i) reveals that: the sameu_(k,i),v_(k,i) may be determined when calculated to N₄=47 (namely,S={2, 3, 4}) and N₁₆=293 (namely, S=I={2, 3, . . . , 16}). Therefore,the calculation may continue only to the fourth sub-group, namely, S={2,3, 4} to obtain u and v of all sub-groups of all sequence groups andreduce the calculation load.

In practice, u and v in use may be quantized according to the foregoingcalculation results to achieve the required precision.

In the foregoing embodiment, selection of the n sequences comes in twocircumstances:

Preferably, n is 1, namely, in the foregoing example, a sequence thatmakes (r_(m)/N_(m)−k/N₁) the smallest is selected and included into thesub-group m.

Preferably, n is a natural number greater than 1, and the value of ndepends on the length difference between sub-group N_(m) and referencesub-group N₁. The sequences corresponding to several basic sequenceindexes near r_(m) that makes (r_(m)/N_(m)−k/N₁) the smallest areincluded into a sub-group. Generally, such sequences are n sequencesclosest to the minimum r_(m), where n depends on the length differencebetween N₁,N_(m). For example, if N_(m) is about 4×N₁, two r_(m)'s maybe included into the group. Generally, n=┌N_(m)/(2N₁)┐ may be selected.In another example, n=└N_(m)/N₁┘ may be selected, where └z┘ is themaximum integer not greater than z. In the sequence sub-group in thiscase, there may be more than one sequence of a certain length. Aftersuch allocation in the system, when using the sequence, the user mayselect any of the allocated n sequences for transmitting, for example,select the sequence that makes (r_(m)/N_(m)−k/N₁) the smallest, secondsmallest, and so on.

In the foregoing embodiment, n sequences are selected, where n ispreferably determined by the sequence group k and sub-group i. Forexample, n≦Q, where Q is the quantity of sequences that meetu_(k,i)≦(r_(i)/N_(i)−c_(k)/N_(p) _(i) )≦v_(k,i), N_(p) ₁ is the lengthof the reference sub-group sequence, and c_(k) is the basic sequenceindex of the sequence with a length of N_(p) ₁ determined by thesequence group k. y_(k,i)=−1/(2N₁) v_(k,i)=1/(2N₁), oru_(k,i)=−1/(2N₁)+1/(4N₂) v_(k,i)=1/(2N₁)−1/(4N₂), u_(k,i)=−½^(θ),v_(k,i)=½^(θ), and so on, where θ is an integer. If u_(k,i) and v_(k,i)are relatively small, for example, u_(k,i)=−1/(2N₁)+1/(4N₂) andv_(k,i)=1/(2N₁)−1/(4N₂), the correlation between any two sequences ofdifferent sequence groups is ensured to be low.

In the foregoing embodiments, the sequence groups may be generated forthe sequences corresponding to partial instead of all modes of occupyingtime frequency resources in the system. For example, the modes ofoccupying time frequency resources may be divided into multiple levelsaccording to the length of the sequence. Each level includes sequencesin a certain length range. For the sequences at each level, the sequencegroups are generated and allocated, as described above.

Specifically, the sequence groups may be allocated dynamically, namely,the sequence in use varies with time or other variables; or the sequencegroups are allocated statically, namely, the sequence in use isconstant. More specifically, the static allocation mode may be usedalone, or the dynamic allocation mode is used alone, or both the dynamicallocation mode and the static allocation mode are used, as detailedbelow:

Preferably, if few radio resources are occupied by the sequence, thesequence groups are allocated dynamically. That is because the sequentlength is small in this circumstance, and there are fewer sequencegroups. For example, as regards the method of “hopping” a sequencegroup: in the foregoing embodiment taking the Zadoff-Chu sequence as anexample, a serial number (r₁) of a reference sequence group is selectedrandomly in the pseudo random mode at the time of transmitting the pilotfrequency, and then the sequence with the index r_(k) in the sub-groupof the same sequence group is calculated out according to the foregoingselection mode.

Preferably, if many radio resources are occupied by the sequence, thesequence groups are allocated statically. For example, in the foregoingembodiment taking the Zadoff-Chu sequence as an example, if the quantity(N) of sequence groups meets the need, the N sequence groups areallocated to each cell, which meets the requirements of averagedinterference between cells without changing with time. Preferably, theradio resources occupied in the system may be divided into two levels.One level is about the sequences that occupy many radio resources, wheredifferent sequence groups are allocated statically; the other level isabout the sequences that occupy few radio resources, where the sequencegroups allocated in the dynamic pseudo random mode. For example, if asequence occupies more than 144 sub-carriers, the sequence length isgenerally greater than or equal to 144, and different sequence groupsare allocated statically; if the sequences in each sequence groupcorrespond to radio resources of less than 144 sub-carriers, thesequence length is generally less than 144, and the sequence groups areallocated in the dynamic pseudo random mode.

If a sub-group contains multiple sequences, including basic sequencesand the sequences of different time cyclic shifts, the sequences may beallocated not only to different users, but also to different cells, forexample, different sectors under a base station. Particularly, if a cellneeds more sequences, for example, if multi-antenna transmitting issupported, each antenna needs to have a different sequence. In thiscase, the minimum length of the sequence in use may be limited toincrease the quantity of basic sequences in the sub-group. Therefore,more basic sequences in the sub-group or more cyclic shifts of the basicsequences may be allocated to the cell. Further, if the sub-group in thesequence group has multiple sequences, the sequence groups may befurther grouped and allocated to different cells, users or channels.

The aforementioned sequences are not limited to Zadoff-Chu sequences,and may be Gauss sequences, other CAZAC sequences, basic sequences,and/or deferred sequences of CAZAC sequences.

Embodiment 2

Corresponding to the aforementioned method for allocating sequencegroups to cells in a specific selection mode in a network, a method forprocessing communication sequences is described. As shown in FIG. 4, theprocess of the method includes:

Step 201: The group number k of the sequence group allocated by thesystem is obtained.

Step 202: N (n is a natural number) sequences are selected from thecandidate sequence collection to form sequences in the sub-group i (i isa serial number of the sub-group) in the sequence group k, where the nsequences make the d(ƒ_(i)(·),G_(k)) function value the smallest, secondsmallest, and third smallest respectively, d(a,b) is a two variablesfunction, G_(k) is a variable determined by the group number k, ƒ_(i)(·)is a function corresponding to the sub-group i determined by the system,and the domain of the function is the candidate sequence collectioncorresponding to the sub-group i.

Step 203: The corresponding transmitting sequences are generatedaccording to the formed sub-group i, and the sequences on thecorresponding time frequency resources are processed.

Processing of communication sequences includes transmitting andreceiving of communication sequences. Receiving of communicationsequences includes calculation related to the generated sequences andreceived signals. Generally, the specific receiving operations includethe calculation for obtaining channel estimation or timesynchronization.

The aforementioned sequences are not limited to Zadoff-Chu sequences,and may be Gauss sequences, other CAZAC sequences, basic sequences,and/or shifted sequences of CAZAC sequences. The processing of sequencesmay be frequency domain processing or time domain processing. Thefunctions in the foregoing method may be consistent with the functionsin the foregoing allocation method, and are not repeated further.

Taking the Zadoff-Chu sequence as an example, if the function d(a,b) isd(a,b)=|(a−b)|, for the sub-group m, the sequence that makes the|r_(m)/N_(m)−k/N₁| value the smallest is selected and included into thesequence group k, thus ensuring higher correlation between sequences andreducing correlation between groups.

In practice, working out the r_(m) indexes that make |r_(m)/N_(m)−k/N₁|the smallest, second smallest, . . . , may induce a general method. Thatis, with an known integer N₁,N₂,e, the integer ƒ needs to make the|e/N₁−ƒ/N₂| value the smallest. Evidently, ƒ is the integer w closest toe·N₂/N₁, namely, the └e·N₂/N₁┘ value rounded down or the ┌e·N₂/N₁┐ valuerounded up. The fewer n sequences are w±1,w±2, . . . .

The transmitter and the receiver may obtain the data through calculationin this way rather than store the data.

Still taking the Zadoff-Chu sequence as an example, if the functiond(a,b) is |(a−b) modu m_(k,i)|, the sub-group numbered p₁ serves as areference sub-group, N_(p) ₁ is the length of the reference sub-groupsequence, c_(k) is the basic sequence index of the sequence with alength of N_(p) ₁ determined by the sequence group k, N_(i) is thelength of the sequence of the sub-group i, and r_(i) is the basicsequence index of the sequence with a length of N_(i) determined by thesequence group k, then, |(a−b)modu m_(k,i)|=|=|(r_(i)/N_(i)−c_(k)/N_(p)₁ )modu m_(k,i)|. Particularly, N_(p) ₁ =N₁ and c_(k)=k may be selected.For the sub-group i=q in the sequence group k, the sequence that makes|(r_(q)/N_(q)−k/N₁) modu m_(k,q)| the smallest is selected and includedinto the sequence group k. Therefore, the selected sequence is the mostcorrelated with the sequence of the reference length in the samesequence group, the correlation of the sequences between differentgroups is further reduced, and the inter-group interference is weaker.

In practice, working out the index r_(q) that makes |(r_(q)/N_(q)−k/N₁)modu m_(k,q)| the smallest may induce a general method, namely,r_(q)=B⁻¹×round(B×k×N_(q)/N₁) where B=1/m_(k,q). B⁻¹ is a natural numberthat meets B×B⁻¹ mod N_(q)=1, and round(z) is an integer closest to z.

A detailed description is given below through examples. With a knowninteger N₁,N₂,e, if m_(k,q)=1, then the integer ƒ needs to make the|(e/N₁−ƒ/N₂ modu 1| value the smallest. Evidently, θ is the integer wclosest to e·N₂/N₁, namely, the └e·N₂/N₁┘ value rounded down or the┌e·N₂/N₁┐ value rounded up. If m_(k,q)=½, then the integer ƒ needs tomake the |(e/N₁−ƒ/N₂) modu ½| value the smallest. ƒ is

${{w \cdot \frac{1 + N_{2}}{2}}\mspace{14mu} {modulo}\mspace{14mu} N_{2}},$

namely,

${{w \cdot \frac{1 + N_{2}}{2}}\mspace{14mu} {mod}\mspace{14mu} N_{2}},$

where W is an integer closest to 2e·N₂/N₁, namely, the └2e·N₂/N₁┘ valuerounded down or the └2e·N₂/N₁┘ value rounded up. If m_(k,q)=⅓ then theinteger ƒ needs to make the |(e/N₁−ƒ/N₂)modu ⅓| value the smallest. WhenN₂ mod 3=0 ƒ is

$\frac{w}{3};$

when N₂ mod 3=1 θ is

${{w \cdot \frac{1 - N_{2}}{3}}\mspace{14mu} {mod}\mspace{14mu} N_{2}};$

when N₂ mod 3=2 ƒ is w·1+N₂/3 mod N₂, where w is an integer closest to3e·N₂/N₁, namely, the └3e·N₂/N₁┘ value rounded down or the └3e·N₂/N₁┘value rounded up. If m_(k,q)=¼, then the integer ƒ needs to make the|(e/N₁−ƒ/N₂) modu ¼| value the smallest. When N₂ mod 2=0, ƒ is

$\frac{w}{4};$

when N₂ mod 4=1, ƒ is

${{w \cdot \frac{1 - N_{2}}{4}}\mspace{14mu} {mod}\mspace{14mu} N_{2}};$

when N₂ mod 4=3, ƒ is

${{w \cdot \frac{1 + N_{2}}{4}}\mspace{14mu} {mod}\mspace{14mu} N_{2}},$

where w is an integer closest to 4e·N₂/N₁, namely, the └4e·N₂/N₁┘ valuerounded down or the ┌4e·N₂/N₁┐ value rounded up.

To sum up, through m_(k,q) storage and simple calculation, the sequencesin the sub-group q in the sequence group k are obtained. According tothe inherent features of m_(k,q) the m_(k,q) storage may be simplified,as detailed below:

m_(k,q) of the sub-group q is symmetric between different sequencegroups k, namely, m_(k,q)=m_(T−k,q), where T is the total number ofsequence groups. Therefore, if m_(k,q) in the case of 1≦k≦T/2 ispre-stored, m_(k,q) in the case of 1≦k≦T can be obtained; or, if m_(k,q)in the case of T/2<k≦T is pre-stored, m_(k,q) in the case of 1≦k≦T canalso be obtained.

If N_(q)≧L_(r), it is appropriate that m_(k,q)=1, where N_(q) is thesequence length of the sub-group q, and L_(r) is determined by thereference sub-group sequence length N_(p) ₁ . Specifically, for N_(p) ₁=N₁=31, L_(r)=139. If N_(q)=139 or above, then m_(k,q)=1. After cyclicextension of the sequence, L_(r)=191. Therefore, when N_(q)=191 orabove, m_(k,q)=1.

The specific values of m_(k,q) corresponding to the sub-group q in thesequence group k may be stored. Specifically, x bits may be used torepresent W different values of m_(k,q), where 2^(x−1)<W≦2^(x); for eachm_(k,q) the x bits that represent the specific values of m_(k,q) arestored. Alternatively, the value selection mode of m_(k,q) may also bestored. For example, when N_(q)≧L_(r), m_(k,q)=1.

In the foregoing embodiment, after the resource occupied by the sequenceis determined, the sequence of the sub-group corresponding to theresource of the current group may be generated in real time according tothe selection mode, without the need of storing. The implementation issimple.

It is understandable to those skilled in the art that all or part of thesteps in the foregoing embodiments may be implemented by hardwareinstructed by a program. The program may be stored in acomputer-readable storage medium such as ROM/RAM, magnetic disk andcompact disk, and the steps covered in executing the program areconsistent with the foregoing steps 201-203.

Embodiment 3

As shown in FIG. 5, an apparatus for processing communication sequencesby using the foregoing communication sequence processing methodincludes:

a sequence selecting unit, adapted to: obtain a group number k of asequence group allocated by the system, and select n (n is a naturalnumber) sequences from a candidate sequence collection to form sequencesin a sub-group i (i is a serial number of the sub-group) in the sequencegroup k (k is the serial number of the sequence group), where the nsequences make the d(ƒ_(i)(·),G_(k)) function value the smallest, secondsmallest, and third smallest respectively, d(a,b) is a two variablesfunction, G_(k) is a variable determined by the group number k, ƒ_(i)(·)is a function corresponding to the sub-group i determined by the system,and the domain of the function is the candidate sequence collectioncorresponding to the sub-group i; and

a sequence processing unit, adapted to: select or generate thecorresponding sequences according to the sequences in the formedsub-group i, and process the sequences on the time frequency resourcescorresponding to the sub-group i.

Specifically, as shown in FIG. 6, the sequence processing unit is asequence transmitting unit adapted to generate the correspondingsequences according to the formed sequences and transmit the sequenceson the corresponding time frequency resources. In this case, thecommunication sequence processing apparatus is a communication sequencetransmitting apparatus.

Specifically, as shown in FIG. 7, the sequence processing unit may be asequence receiving unit adapted to generate the corresponding sequencesaccording to the formed sequences and receive the sequences on thecorresponding time frequency resources. In this case, the communicationsequence processing apparatus is a communication sequence receivingapparatus. The receiving processing generally includes calculationrelated to the generated sequences and received signals. Generally, thespecific receiving operations include the calculation for obtainingchannel estimation or time synchronization.

The relevant functions and specific processing in the communicationsequence processing apparatus are consistent with those in the forgoingallocation method and processing method, and are not repeated further.The aforementioned sequences are not limited to Zadoff-Chu sequences,and may be Gauss sequences, other CAZAC sequences, basic sequences,and/or deferred sequences of CAZAC sequences. The processing ofsequences may be frequency domain processing or time domain processing.

In the foregoing communication sequence processing apparatus, thesequence selecting unit selects a sequence compliant with theinterference requirement directly in a specific selection mode, withoutthe need of storing the lists about the correspondence of sequences,thus saving communication resources as against the conventional art.

Although exemplary embodiments have been described through theapplication and accompanying drawings, the claims are not limited tosuch embodiments. It is apparent that those skilled in the art can makevarious modifications and variations to the embodiments withoutdeparting from the spirit and scope of the claims.

What is claimed is:
 1. A method for allocating sequences in acommunication system, comprising: dividing, by a communication system,sequences in a sequence group into multiple sub-groups, each sub-groupcorresponding to a mode of occupying time frequency resources; andallocating, by the communication system, a sequence of the sub-groups ina sequence group k to a channel, wherein the sequence of a sub-group isatisfies r_(i)=└N_(i)c_(k)/31+½┘, r_(i) is a basic sequence index in acandidate sequence collection, N_(i) is a length of a sequence in thecandidate sequence collection, and c_(k) is a basic sequence index of asequence with a length of 31 determined by the sequence group k.
 2. Themethod of claim 1, wherein the sequences correspond to at least one of:Zadoff-Chu sequences and Gauss sequences.
 3. A method for processingsequences in a communication system by at least one of a base stationand a user equipment, comprising: obtaining, a group number k of asequence group allocated by the system; generating, correspondingsequences according to the sequences in a formed sub-group; wherein thesequence of a sub-group i satisfies r_(i)=└N_(i)c_(k)/31+½┘, whereinr_(i) is a basic sequence index in a candidate sequence collection, andN_(i) is the length of a sequence in the candidate sequence collection,c_(k) is a basic sequence index of a sequence with a length of 31determined by the sequence group k; and communicating, according to thegenerated sequences on time frequency resources corresponding to thesub-group i.
 4. The method of claim 3, wherein the sequences correspondto at least one of: Zadoff-Chu sequences and Gauss sequences.
 5. Themethod of claim 3, wherein communicating according to the generatedsequences on time frequency resources corresponding to the sub-group icomprises: sending, according to the generated sequences on timefrequency resources corresponding to the sub-group i; or receiving,according to the generated sequences on time frequency resourcescorresponding to the sub-group i.
 6. A method for processing sequencesin a communication system, comprising: obtaining, by a user equipment, agroup number k of a sequence group allocated by a base station;generating, by the user equipment, corresponding sequences according tosequences in a formed sub-group; wherein the sequence of a sub-group isatisfies r_(i)=└N_(i)c_(k)/31+½┘, wherein r_(i) is a basic sequenceindex in a candidate sequence collection, and N_(i) is the length of asequence in the candidate sequence collection, c_(k) is a basic sequenceindex of a sequence with a length of 31 determined by the sequence groupk; and sending, by the user equipment, according to the generatedsequences on time frequency resources corresponding to the sub-group i.7. The method of claim 6, wherein the sequences correspond to at leastone of: Zadoff-Chu sequences and Gauss sequences.
 8. A communicationsystem for allocating sequences, comprising: a processor configured todivide sequences in a sequence group into multiple sub-groups, whereineach sub-group corresponds to a mode of occupying time frequencyresources, and allocate a sequence group of the sub-groups in a sequencek to at least one of: a base station, a cell, a user equipment and achannel; wherein a sequence of a sub-group i satisfiesr_(i)=└N_(i)c_(k)/31+½┘, wherein r_(i) is a basic sequence index in acandidate sequence collection, and N_(i) is the length of a sequence inthe candidate sequence collection, c_(k) is a basic sequence index of asequence with a length of 31 determined by the sequence group k.
 9. Thesystem of claim 8, wherein the sequences correspond to at least one of:Zadoff-Chu sequences and Gauss sequences.
 10. A sequence processingapparatus, comprising: a sequence obtaining unit configured to obtain agroup number k of a sequence group allocated by a system, a sequenceprocessing unit configured to generate corresponding sequences accordingto sequences in the formed sub-group i, wherein a sequence of asub-group i satisfies r_(i)=└N_(i)c_(k)/31+½┘, wherein r_(i) is a basicsequence index in a candidate sequence collection, and N_(i) is thelength of a sequence in the candidate sequence collection, c_(k) is abasic sequence index of a sequence with a length of 31 determined by thesequence group k, and the sequence processing unit is further configuredto process, according to the generated sequences, on time frequencyresources corresponding to the sub-group i.
 11. The sequence processingapparatus of claim 10, wherein the sequences correspond to at least oneof: Zadoff-Chu sequences and Gauss sequences.
 12. The sequenceprocessing apparatus of claim 10, wherein in processing, according tothe generated sequences, on time frequency resources corresponding tothe sub-group, the sequence processing unit is further configured to:send according to the generated sequences on time frequency resourcescorresponding to the sub-group i, or receive according to the generatedsequences on time frequency resources corresponding to the sub-group i.13. A user equipment, comprising: a sequence obtaining unit configuredto obtain a group number k of a sequence group allocated by a basestation, a sequence processing unit configured to generate correspondingsequences according to the sequences in the formed sub-group i, whereinthe sequence of a sub-group i satisfies r_(i)=└N_(i)c_(k)/31+½┘, whereinr_(i) is a basic sequence index in a candidate sequence collection, andN_(i) is the length of a sequence in the candidate sequence collection,c_(k) is a basic sequence index of a sequence with a length of 31determined by the sequence group k, and the sequence processing unit isfurther configured to send according to the generated sequences on timefrequency resources corresponding to the sub-group i.
 14. The userequipment of claim 13, wherein the sequences correspond to at least oneof: Zadoff-Chu sequences and Gauss sequences.